System for reducing thermal transfer between cells in a battery

ABSTRACT

A thermal transfer barrier is disclosed that is positionable adjacent to an electrical storage cell having a vent configured to release gasses from the cell. The thermal transfer barrier may comprise a barrier member having a first side for orienting toward the vent on the cell. The first side is contoured in a manner configured to collect gas directed toward the first side of the barrier member from the vent when released from the vent and guide the collected gas away from a cell positioned adjacent to the cell.

BACKGROUND

1. Field

The present disclosure relates to batteries, and more particularlypertains to a new system for reducing thermal transfer between cells ina battery to reduce the possibility of a cascade thermal runaway ofcells in the battery.

2. Description of the Prior Art

The use of portable devices for various tasks has become ubiquitous, andwhile the miniaturization of various components that make up thesedevices is a part of their increasing popularity, and the ability topower these devices for longer and longer time periods has also added tothe portability and ease of use of the devices. Contributing to theimprovement in the ability to power these portable devices is thedevelopment of new battery technologies with seemingly ever increasingcharge capacities in smaller and smaller packages.

These developments have not been without their occasional drawbacks, andone example of this is the development of lithium ion batterytechnology. While delivering relatively greater charge capacities inrelatively smaller packages, the lithium ion cells have the potential togenerate very high temperatures if there is a failure in the circuitryor structure of the cell that causes, for example, a short circuit.These high temperatures are not only damaging to the battery and thedevice in which the lithium ion cell is incorporated or attached, butcan cause other damage by fire if the battery continues to malfunction.

More specifically, the effort to increase the density of the cells toprovide a greater charge capacity in a smaller space has tended to makethe cells more vulnerable to defects and damage that can cause suchfailures. The increasing density has been achieved through manufacturingtechniques that make the components of the cell thinner, such as theseparator between anode and cathode. Thus, the manufacturing methodshave become more critical not only to the operation of the cell but alsoto the safety of the cell, especially as the cells become denser. Forexample, the presence of small metallic dust particles in the cell cancause a short circuit in the cell if these particles come into contactwith the oppositely charged parts of the cell. Elimination of all ofthese dust particles from the manufacturing process may be virtuallyimpossible.

While a mild short may generate only a small amount of heat and may leadto an accelerated degree of self-discharge, the presence of enough metalparticles at one location can produce a major electrical short and amuch larger current flow between the positive and negative plates,causing a more significant temperature rise and possibly the conditionsometimes referred to as “thermal runaway” in which flaming gases may bevented from the cell.

During thermal runaway of a cell, the heat generated in themalfunctioning cell can be transferred to an adjacent cell in thebattery package, causing the adjacent cell to become thermally unstable.This heat transfer can lead to a chain reaction in which failure of acell cascades to an adjacent cell, and the process may be repeated toother cells. Thus, not only can the malfunctioning cell of the batterybe affected, but cells adjacent to the malfunctioning cell can beexposed to the heat generated by the malfunction and the performance andoperation of the adjacent cell can be affected, even to the point thatthe adjacent cells can be caused to also malfunction. Typically, a cellwill include a vent that allows the hot gases to escape from theinterior of a cell when pressures in the interior of the cell exceed athreshold level. The vent is typically located toward or on the end ofthe cell, which often has an elongated cylindrical shape. Thepositioning of the vent are the end of the cell, which is often next toan adjacent cell, can allow the hot, pressurized gases escaping from themalfunctioning cell to contact, and heat, the adjacent cell, which canin turn cause overheating and excess pressure in the adjacent cell.

It is therefore believed that there is a need in the art for a devicethat increases the safety of operation of cells in a battery, especiallybut not limited to lithium ion batteries, to decrease the possibilitythat a malfunction in one cell of the battery is able to propagate toanother adjacent cell.

SUMMARY

In view of the foregoing disadvantages inherent in the known batterydesigns, the present disclosure describes a new system for reducingthermal transfer between cells in a battery which may be utilized toreduce the possibility of a cascade thermal runaway of cells in a thebattery.

The present disclosure relates to a new thermal transfer barrier that ispositionable adjacent to an electrical storage cell having a ventconfigured to release gasses from the cell. The thermal transfer barriercomprises a barrier member having a first side for orienting toward thevent on the cell. The first side is contoured in a manner configured tocollect gas directed toward the first side of the barrier member fromthe vent when released from the vent and guide the collected gas awayfrom a cell positioned adjacent to the cell.

In another aspect, a battery assembly comprises at least two electricalstorage cells with at least one of the cells having a vent configured torelease gasses from the cell. A thermal transfer barrier is positionedbetween the at least two cells, and the barrier is positioned adjacentto the vent on the at least one cell such that gasses released throughthe vent are directed toward the thermal transfer barrier. The thermaltransfer barrier forms a thermal barrier between the cells.

In one yet another aspect, a battery assembly comprises a housingdefining an interior and at least two electrical storage cells locatedin the interior of the housing. A thermal transfer barrier is located inthe interior of the housing and is positioned between the at least twocells in the housing. The thermal transfer barrier is formed of amaterial having a greater insulation capability than a material of thehousing.

The foregoing is a general outline of some-of the more significantaspects of the disclosure, and the detailed description of thisapplication that follows discloses additional features of the disclosurewhich form the subject matter of the claims appended hereto.

The advantages of the various embodiments of the present disclosure,along with the various features of novelty that characterize theembodiments, are disclosed in the following descriptive matter andaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure will be better understood when consideration is given tothe following detailed description thereof. Such description makesreference to the annexed drawings wherein:

FIG. 1 is a schematic perspective view of a new thermal transfer barrieraccording to the present disclosure.

FIG. 2 is a schematic sectional view of the thermal transfer barrier,according to an illustrative embodiment, taken along line 2-2 of FIG. 1.

FIG. 3 is a schematic perspective view of the thermal transfer barrierpositioned between two adjacent cells of a battery, according to anillustrative embodiment.

FIG. 4 is a schematic perspective view of a battery housing with thethermal transfer barrier, according to an illustrative embodiment.

FIG. 5 is a schematic sectional view of the battery housing includingthe barrier, according to an illustrative embodiment.

FIG. 6 is a schematic sectional view of the battery housing includingthe barrier, according to an illustrative embodiment.

DESCRIPTION OF PREFERRED EMBODIMENTS

With reference now to the drawings, and in particular to FIGS. 1 through6 thereof, the system for reducing thermal transfer between cells in abattery of the present disclosure generally includes a thermal transferbarrier designated by the reference numeral 10 in this description.

In the following detailed description of preferred embodiment and otherembodiments according to the present disclosure, reference is made tothe accompanying drawings which form a part hereof, and in which isshown by way of illustration specific preferred embodiments in which theinvention may be practiced. These embodiments are described insufficient detail to enable those skilled in the art to practice theinvention, and it is to be understood that other embodiments may beutilized and that logical, mechanical and electrical changes may be madewithout departing from the spirit or scope of the invention. To avoiddetail not necessary to enable those skilled in the art to practice theinvention, the description may omit certain information known to thoseskilled in the art. The following detailed description is, therefore,not to be taken in a limiting sense, and the scope of the presentinvention is defined only by the appended claims.

The present disclosure relates to a thermal transfer barrier 10 that ishighly suitable for use in a battery assembly 12 that may comprise atleast two electrical storage cells 14, 16 that store electrical energyand discharge that electrical energy between an anode and a cathode,such as electrolytic cells, although the barrier 10 of the disclosure isnot limited to such applications. The thermal transfer barrier 10 of thedisclosure is suitable for use in a battery 12 that includes more thantwo cells, especially for those batteries incorporating several cells,but this description will proceed in terms of two cells 14, 16. Thethermal transfer barrier 10 is also especially suitable for use in abattery 12 in which the cells 14, 16 are positioned in relatively closeproximity to each other in the battery.

While the thermal transfer barrier 10 is useful with virtually any typeof electrical storage cell technology, it is especially suitable for usewith storage cell technologies that generate, or have the potential togenerate, large amounts of heat either in normal operation or during aperiod of malfunction. One storage cell technology that may experiencethese conditions is lithium ion-based storage. Although the usefulnessof the barrier 10 is not limited to this type of cell technology, thedescription will be in terms of the lithium-based technology, which hasmany similarities to other electrolytic cell technologies. The cells 14,16 are typically (but not necessarily) elongated and cylindrical inshape, which provides ease of manufacture, high energy density and goodmechanical stability. One common size is designated as “18650”, in which“18” denotes the diameter is 18 mm and “650” denotes the length is 65mm. Other cell types, such as for example button or prismatic, may beused with the system of the disclosure.

Significantly, the cells 14, 16 may be provided with a vent 18 torelease pressure from the interior of the cell developed under extremeconditions such as excessive overcharging or physical damage to thestructure of the cell. Opening of the vent 18 may occur at, for example,pressures between of approximately 150 psi to approximately 200 psi(approximately 10 Bar to approximately 13.5 Bar). The vent 18 of thecell 14, 16 is typically located on an end of the elongated cell, andsometimes on or near the positive terminal or anode of the cell.

The battery assembly 12 may include a housing 20 which substantiallyencloses the cells 14, 16 of the battery and may perform other functionsthat are not relevant here, such as providing structure for mounting thebattery on a larger device, such as, for example, a portable computer.The housing 20 may form at least one cavity 22, with one or more of thecells 14, 16 being positioned in the cavity 22. In some embodiments ofthe housing 20, two cavities 22, 24 may be formed.

The cavities 22, 24 may be elongated to hold one, or more than one, ofthe cells 14, 16, particularly when the shape of cells 14, 16 iselongated. When multiple cells 14, 16 are positioned in a cavity, thecells 14, 16 are often positioned in an end to end relationship, withthe end (often the anode terminal) of one of the cells 14, 16 beingpositioned adjacent to the end (often the cathode terminal) of anotherone of the cells 14, 16. This configuration typically positions the vent18 on one end of the cell in an adjacent relationship to the end ofanother cell in the battery, and may orient the vent so that emissionsfrom the vent are directed at another cell in the battery. In otherconfigurations, the ends of some cells of a multiple cell battery arepositioned such that the vent on a cell is adjacent to or directedtoward an adjacent cell that may or may not be positioned in an end toend relationship with the cell. In either of these configurations, orothers not mentioned, gases that are vented from one cell are directedtoward, and will likely come in contact with, another cell in thehousing of the battery 12. As previously noted, the hot gases ventedfrom one cell can contact an adjacent cell in the battery 12 and causethat adjacent cell to also overheat and vent hot gas. Due to the hot andpressurized character of the gases emanating from the vent 18, anadjacent cell does not have to be in direct contact with the ventingcell to be affected by the venting gases, and even if the cells aresomewhat spaced from each other, the venting gas of one cell may affectanother cell in the battery. The encasement of walls of the housing 12may trap the gases and further accentuate the heat problem. The adjacentcells 14, 16 may be located sufficiently proximate to each other topermit gases exiting the vent 18 of one cell 14 to contact the other ofthe cells 16.

The system of the disclosure utilizes the thermal transfer barrier 10for positioning between two cells 14, 16, especially when the two cellsare positioned adjacent to each other. The thermal transfer barrier 10acts as an obstacle to the movement of heat through the barrier. Thebarrier 10 may not function as a complete barrier or obstruction to themovement of heat through the barrier 10, although the barrier 10 shouldprovide a substantial impediment to the movement of heat therethrough.The thermal transfer barrier 10 may have an additional function ofguiding or directing or diverting gases which may be vented through thevent 18 of a cell away from an adjacent cell.

In various embodiments, the barrier 10 comprises an element that isinterposed between cells, such as, for example cells that wouldotherwise be adjacent to each other if not for the presence of thebarrier 10. In some configurations, the barrier 10 is positionedadjacent to the location of the vent 18 on one of the cells so that anygases that are vented from the vent 18 of the one cell are directed awayfrom the other cell. The barrier 10 may thus be positioned between endsof adjacent cells 14, 16 in or on a battery housing or other structureholding the cells in position.

In some embodiments, the barrier 10 comprises a barrier member 26 thatmay have a disk-like configuration. The barrier member 26 may have aperimeter 28 with a shape that approximates the size and shape of thecells 14, 16 between which the barrier member 26 is positioned. Theperimeter 28 of the barrier member 26 may have an edge, and in someconfigurations the perimeter edge may be substantially circular. Thecircular disc configuration may facilitate the positioning between cellsin a cavity 22 of the housing 20.

In other embodiments, the barrier 10 comprises a barrier wall 30 thatmay form a portion of the housing 20, and the barrier wall 30 may beincorporated into the battery housing 20. The barrier wall 30 may bepositioned between and form two cavities 22, 24 of the housing 20.

In the various configurations of the embodiments, the thermal transferbarrier 10 may have a first side 32 for positioning toward a first one14 of the cells, and may be positioned toward the vent 18 of the cell14. The surface 34 of the first side 32 may be contoured to collectgases escaping from the vent 18 of the first cell and may be contouredto direct those escaping gases in a direction away from a second one 16of the cells which is positioned adjacent to the barrier 10. The contourof the surface 34 of the first side 32 barrier 10 which is positionedbetween the cells 14, 16 is thus able to divert gases exiting the vent18 of the cell 14 from an unrestricted path out of the vent 18 and awayfrom the cell 16. The contour of the surface 34 may extend into thefirst side 32 of the barrier 10, and the contour may be such that aportion of the surface 34 is substantially concave in character. Thecontour of the surface 34 may include a main portion or region 36, whichmay be substantially centered on the first side 32 of the barrier 10.The main region 36 may be substantially circular perimeter shape,although the invention is not so limited. The main region 36 may be atleast partially surrounded by a ridge 38. The ridge 38 may besubstantially annular in shape or configuration, such that the ridgeforms a raised area or region about the relatively depressed region ofthe main region. The ridge 38 thus facilitates the movement of gasesexpelled in the direction of the first side 32 are guided or directedtoward the main region 36. The contour of the surface 34 of the firstside 32 may also include a channel region 40 extending outwardly fromthe main region 26 and through the ridge 38. The channel region mayextend radially outward from the main region 36. The path of the channelregion 40 may extend substantially perpendicularly to a longitudinalaxis of the cell adjacent to which the barrier is positioned. Thechannel region 40 is thereby able to channel or direct gases collectedin the main region 36 of the contour of the surface 34 of the first side32 in a desired direction, while the presence of the barrier 10 tends toblock the gases from reaching and contacting the adjacent cell.

The thermal transfer barrier 10 may have a second side 42 that ispositioned toward the second cell 16 when the first side 32 ispositioned toward the second side 42. Optionally, the surface of thesecond side 42 may be contoured in a manner similar to the contour ofthe first side to direct gasses from the second cell 16 in a directionaway from the first cell 14 that may be positioned adjacent to the firstside 32.

In various embodiments, the thermal transfer barrier 10 comprises athermally insulative material that resists the transfer or communicationof heat from one side of the barrier to an other side of the barrier sothat heat transferred to the barrier by one cell is not transferred inany meaningful degree to the cell on the other side of the barrier. Forexample, the housing 20 of a battery 12 is commonly formed of ahydrocarbon plastic which may be distorted or even caused to catch fireby intense heat, such as the heat that is present in the gases that maybe vented from a cell, which maybe at 300 degrees Fahrenheit or more.The thermal transfer barrier may be formed of a material with higherresistance to deformation when exposed to heat of the temperature of thegases exhausted by the cell when a malfunction occurs. The material ofthe barrier 10 may differ from the material which forms the remainder ofthe housing in the heat resistance characteristic. Thus, those portionsof the housing 20 that are not directly exposed to the heated outgasesmay be formed of cheaper and lighter weight materials while the barrier10, which may be directly exposed to the outgases, is formed of arelatively more heat resistant material.

In some embodiments, the thermal transfer barrier 10 is formed of amaterial that experiences a phase change when exposed to the heat of thetemperature of the hot gasses escaping from the vent 18, so that theheat absorption of the barrier is increased.

The thermal transfer barrier 10 may comprise an electricallynon-conductive, or electrically insulative, material that does notconduct electricity between the adjacent cells. In some embodiments, aconductor 44 may be utilized to electrically connect a terminal on oneside of the barrier 10 to a terminal on the other side of the barrier.

The thermal transfer barrier 10 may further comprise a non-flammablematerial that is not readily ignited and thus is unlikely to combustwhen exposed to high temperatures such as the range of temperatures thatmight be present when gas is exhausted through the vent of amalfunctioning cell for, for example, the lithium-ion type.

The thermally-insulative, electrically non-conductive, and non-flammablematerial of the barrier 10 may comprise a non-metallic material, and maycomprise a non-hydrocarbon-based material. Illustratively, the materialof the barrier may comprise a ceramic material, although those skilledin the art are aware of other suitable thermally and electricallyinsulating materials that are non-flammable.

Aspects of the invention are disclosed in the foregoing description andrelated drawings directed to specific embodiments of the invention.Alternate embodiments may be devised without departing from the scope ofthe invention. Additionally, well-known elements of the invention willnot be described in detail or will be omitted so as not to obscure therelevant details of the invention. Although specific embodiments havebeen illustrated and described herein, it should be appreciated that anyarrangement calculated to achieve the same purpose may be substitutedfor the specific embodiments shown. This disclosure is intended to coverany and all adaptations or variations of various embodiments. It is tobe understood that the above description has been made in anillustrative fashion, and not a restrictive one. Combinations of theabove embodiments, and other embodiments not specifically describedherein will be apparent to those of skill in the art upon reviewing theabove description. Thus, the scope of various embodiments includes anyother applications in which the above compositions, structures, andmethods are used.

As the following claims reflect, inventive subject matter lies in lessthan all features of a single disclosed embodiment. Thus the followingclaims are hereby incorporated into the Detailed Description, with eachclaim standing on its own as a separate preferred embodiment. In theappended claims, the terms “including” and “in which” are used as theplain-English equivalents of the respective terms “comprising” and“wherein,” respectively. Moreover, the terms “first,” “second,” and“third,” etc. are used merely as labels, and are not intended to imposenumerical requirements on their objects. Further, where the term“substantially” is used, it is intended to mean “for the most part” or“being largely but not wholly that which is specified”.

1. A thermal transfer barrier positionable adjacent to an electricalstorage cell having a vent configured to release gasses from the cell,the thermal transfer barrier comprising: a barrier member having a firstside for orienting toward the vent on the cell, the first side beingcontoured in a manner configured to collect gas directed toward thefirst side of the barrier member from the vent when released from thevent and guide the collected gas away from a cell positioned adjacent tothe cell.
 2. The thermal transfer barrier of claim 1 wherein the contourof the first side includes a concave-shaped region.
 3. The thermaltransfer barrier of claim 2 wherein the contour of the first sideincludes a channel in communication with the concave-shaped region. 4.The thermal transfer barrier of claim 3 wherein the concave region issubstantially centrally located on the barrier member, and the channelof the contour extends radially outward from the concave-shaped region.5. A battery assembly, comprising: at least two electrical storagecells, at least one of the cells having a vent configured to releasegasses from the cell; and a thermal transfer barrier positioned betweenthe at least two cells, the thermal transfer barrier being positionedadjacent to the vent on the at least one cell such that gasses releasedthrough the vent are directed toward the thermal transfer barrier;wherein the thermal transfer barrier forms a thermal barrier between thecells.
 6. The battery assembly of claim 5 wherein the thermal transferbarrier comprises an electrically non-conductive material.
 7. Thebattery assembly of claim 5 wherein the thermal transfer barriercomprises a non-flammable material.
 8. The battery assembly of claim 5wherein the thermal transfer barrier comprises a ceramic material. 9.The battery assembly of claim 5 wherein the thermal transfer barrier hasa first side being contoured in a manner configured to collect gasdirected toward the first side of the barrier from the vent whenreleased from the vent and guide the collected gas away from the cellpositioned adjacent to the at least one cell.
 10. The battery assemblyof claim 9 wherein the contour of the first side includes aconcave-shaped region.
 11. The battery assembly of claim 10 wherein thecontour of the first side includes a channel in communication with theconcave-shaped region.
 12. The battery assembly of claim 11 wherein theconcave region is substantially centrally located on the barrier member,and the channel of the contour extends radially outward from theconcave-shaped region.
 13. A battery assembly comprising: a housingdefining an interior; at least two electrical storage cells located inthe interior of the housing; and a thermal transfer barrier located inthe interior of the housing, the thermal transfer barrier beingpositioned between the at least two cells in the housing; wherein thethermal transfer barrier is formed of a material having a greaterinsulation capability than a material of the housing.
 14. The batteryassembly of claim 13 wherein the thermal transfer barrier comprises anelectrically non-conductive material.
 15. The battery assembly of claim13 wherein the thermal transfer barrier comprises a non-flammablematerial.
 16. The battery assembly of claim 13 wherein the thermal-transfer barrier comprises a ceramic material.
 17. The battery assemblyof claim 13 wherein the thermal transfer barrier has a first side beingcontoured in a manner configured to collect gas directed toward thefirst side of the barrier from the vent when released from the vent andguide the collected gas away from the cell positioned adjacent to the atleast one cell.
 18. The battery assembly of claim 17 wherein the contourof the first side includes a concave-shaped region.
 19. The batteryassembly of claim 18 wherein the contour of the first side includes achannel in communication with the concave-shaped region.
 20. The batteryassembly of claim 13 wherein the thermal transfer barrier forms a wallin the housing positioned between the at least two cells in the housing.